Most conventional eyebrow embroidery machines are composed of a transmission mechanism and a needle mechanism, and the transmission mechanism can drive an eyebrow embroidery needle in the needle mechanism to move reciprocally along the central axis of the eyebrow embroidery machine, such that an eyebrow embroidery operator can attach a liquid dye at the tip of the eyebrow embroidery needle to form a predetermined tattoo on a human body, and discard the eyebrow embroidery needle used after the embroidery job, and another brand new eyebrow embroidery needle is used for the next embroidery job to assure a sanitary usage and prevent blood-borne infectious diseases. However, the aforementioned needle mechanism generally includes a bushing and an eyebrow embroidery needle, and the needle head of the eyebrow embroidery needle is passed through the bushing and exposed to the outside from the bushing, and thus the dye adhered onto the eyebrow embroidery needle before the embroidery job takes place or the blood adhered onto the eyebrow embroidery needle before the embroidery job finishes is generally carried into the bushing, since the eyebrow embroidery needle is moved continuously back and forth. In the meantime, the dye or blood attached onto the internal wall surface of the bushing flows back into the motor along the internal wall surface of the bushing due to the capillary action, and causes an electric short circuit. The dye at the needle head may flow back into the bushing to contaminate the motor, if an operator places the eyebrow embroidery machine horizontally during the embroidery job. Thus, related cosmetic manufacturers generally design an eyebrow embroidery machine with an anti-backflow structure to avoid the aforementioned problems.
In FIG. 1, an eyebrow embroidery machine 1 comprises a transmission mechanism 11 and a needle mechanism 13, wherein the transmission mechanism 11 includes a motor 111, and the motor 111 includes a transmission shaft 113 and drives the transmission shaft 113 to displace along the central axis of the eyebrow embroidery machine. The transmission mechanism 11 further includes a power cord 115 connected to an end away from the transmission shaft 113 for supplying electric power required for the operation of the motor 111. The needle mechanism 13 further includes a connecting sleeve 131, an eyebrow embroidery bushing 133, a needle bushing 135, an anti-backflow plastic cover 136 and an eyebrow embroidery needle 137, wherein an end of the connecting sleeve 131 is coupled to an end of the transmission mechanism 11, and another end of the connecting sleeve 131 is screwed to an end of the eyebrow embroidery bushing 133, and an end of the anti-backflow plastic cover 136 is sheathed onto the periphery of the needle bushing 135, and another end is clamped between an end of the transmission mechanism 11 and the connecting sleeve 131, and the needle bushing 135 is installed in the connecting sleeve 131. In addition, an end of the needle bushing 135 is screwed with the transmission shaft 113 of the transmission mechanism 11, and another end of the needle bushing 135 is inserted with the eyebrow embroidery needle 137, and the eyebrow embroidery needle 137 extends to the outside from another end of the eyebrow embroidery bushing 133 and is capable of attaching a liquid dye, so that the dye or blood flowing back into the eyebrow embroidery bushing 133 will be blocked by the anti-backflow plastic cover 136 and cannot flow into the transmission mechanism 11, so as to prevent a short circuit of the motor 111 installed in the transmission mechanism 11 or a contamination of the transmission shaft 113. However, when the eyebrow embroidery machine 1 is used, other problems may occur. In FIG. 1, the dye or blood flowing back into the eyebrow embroidery bushing 133 is blocked by the anti-backflow plastic cover 136, but the dye or blood may be accumulated at the screwed position (as indicated by the dotted circle A in FIG. 1) between the connecting sleeve 131 and the eyebrow embroidery bushing 133. Particularly, if an operator places the eyebrow embroidery machine 1 in a horizontal position, the aforementioned situation may occur easily. In general, two adjacent screw threads in a screw threaded structure are not arranged closely adjacent with each other, but a gap exists between any two adjacent screw threads, such that the dye or blood accumulated at the screwed position between the connecting sleeve 131 and the eyebrow embroidery bushing 133 will leak from the gap between the screw threads and flow to the external periphery of the eyebrow embroidery bushing 133. Particularly, when the operator turns the eyebrow embroidery bushing 133 to adjust the length of the needle head exposed from the eyebrow embroidery needle, the speed of the leakage and the flow of the dye will be increased, resulting in the inconvenience of holding the eyebrow embroidery machine and the contamination to the operator's hand that ruins the product image and hygiene of the eyebrow embroidery machine.
In FIG. 1, the transmission mechanism 11 and the needle mechanism 13 are connected by screwing the connecting sleeve 131 with the transmission mechanism 11, as well as screwing the needle bushing 135 with the transmission shaft 113, such that when the operator changes the needle mechanism 13, the operator has to align the transmission shaft 113 and the needle bushing 135 at the corresponding screwed position precisely before the transmission mechanism 11 and the needle mechanism 13 can be installed successfully. Since the needle bushing 135 is smaller, therefore the operator may shift from the predetermined screwed position, which makes the installation more difficult and inconvenient, and results in a longer waiting time before having an eyebrow embroidery service. Obviously, the conventional eyebrow embroidery machine still has problems in its use and installation. Therefore, it is an important subject for related cosmetic manufacturers to design and develop an eyebrow embroidery machine to achieve the effects of overcoming the shortcomings of the prior art, and preventing the dye from flowing back into the motor or leaking from the external periphery of the eyebrow embroidery bushing, so as to facilitate the operator's installation.